As stated above, the measure of effect size will be the Pearson Product Moment correlation coefficient (r). For this study, the effect size of r = .50 was chosen as the smallest effect size that would be clinically meaningful, and a sample size of 26 was calculated as necessary to obtain power of 81% and a 95% confidence interval (r = .13 to r = .75) that would not include zero (Rosenthal, 1991).